As one kind of ink jet recording head, a recording head is known that discharges ink droplets utilizing energy generated by an electrothermal converting element. In this kind of recording head, as shown in FIG. 13, a silicon liquid discharge substrate 204 that comprises a discharge port 200 which discharges ink droplets, a liquid chamber 201 in which ink discharged from the discharge port 200 is temporarily accumulated, liquid supply ports 202 which communicate with the liquid chamber 201, and electrothermal converting elements 203 which impart discharge energy to the ink in the liquid chamber 201 is mounted in an integrated condition on an alumina supporting member 205. More specifically, the underside of the liquid discharge substrate 204 and the top surface of the supporting member 205 are directly bonded by an epoxy bonding agent 206 and, through an ink channel formed by the opposing boundary surfaces 207 of the bonding agent 206, the liquid supply port 202 of the liquid discharge substrate 204 communicates with a liquid supply hole 208 that is provided in the supporting member 205 (for a more detailed description, for example, refer to the ink jet recording head described in Japanese Patent Application Laid-Open No. H10-44420).
The electrothermal converting element 203 generates a phase change in the ink inside the liquid chamber 201 by imparting thermal energy to the ink, thereby causing minute ink droplets to be discharged from the discharge port 200 by the pressure of air bubbles generated in the ink at that time. Surplus heat is transmitted to the supporting member 205 through the liquid discharge substrate 204 and dissipated.
In this type of ink jet recording head, because ink droplets are discharged utilizing the pressure of air bubbles generated when ink develops into foams, when the temperature of the liquid discharge substrate becomes high the discharge control becomes difficult, resulting in disadvantages such as the erroneous discharge of ink droplets. Therefore, conventional ink jet recording apparatuses are equipped with a mechanism that temporarily suspends discharge operations when the temperature of the liquid discharge substrate has become high. Meanwhile, there is an ever-growing trend towards densification of electrothermal converting elements in order to respond to demands for high-speed recording at higher resolutions, and the electrical power consumption of electrothermal converting elements is also continuing to increase. As a result, the temperatures of liquid discharge substrates during operation are tending to increase, and if this trend continues it is anticipated that the recording heads will frequently fall into a suspended state during operation.